Pros

Cons

Since early 2007, Helix has been a sort of 'secret weapon' for a select few savvy synthesists. It spent a great deal of time in beta and was freely downloadable.

Those who tried it found Helix to be a powerful ally, capable of everything from warm analogue timbres to steely digital sweeps. It was very much a synthesist's synth, but its busy interface could be too much for the uninitiated.

Along with its new price tag of $149, Helix now comes with a fine set of new clothes, which goes a long way towards remedying the interface problems, and it has numerous additional features, too. Still a cross-platform VST plug-in, it also works with FXpansion's AU wrapper.

Oscillators

Helix's signal path begins with four oscillators, each of which can be used in one of four modes. You can control the pitch, pan, phase, amplitude and stability.

Additional knobs appear depending on which one you plump for, though there is a Morph control that's common to three of the oscillator modes - it can operate as a modulation destination, to be wobbled by LFOs and shifted by envelopes.

The Analog oscillator type is a simple pulse wave affair, sporting a single Morph knob to adjust the pulse width. Also included is a Noise generator, which only offers a Stereo button.

The String oscillator offers more options for tweaking and deviates from the norm by modelling a pair of strings (think 12-string guitar). A Damp function imparts a muted sound, while a Frequency Spread knob detunes the strings.

More familiar are controls for Low Pass and Pulse Width Modulation (attached to the Morph mod destination). Finally, there's a Crosstalk knob that determines how much energy from one string 'leaks' into the other.

Helix's Waveshaping oscillator is by far its most impressive and appealing feature. Imagine the flexibility of a waveshaping oscillator such as those found in Z3TA+ or Absynth but with the built-in motion of a classic wavetable affair, a la the PPG Wave.

For each voice, Helix gives you the ability to pick from around 30 basic waveforms - or even import your own - before twisting the shape via a plethora of controls. Once you've defined two waves, the Morph parameter is used to glide between them. This is truly powerful and inspiring stuff.

Helix also sports a stupendous Unison function that piles the waveforms 16 high for each oscillator. It's possible to offset the initial phase of each unison voice, too.

Sound sculpting

After you've wrangled with your waveforms, you can shuttle them through three stages apiece of filtering and shaping (mostly distortion, though you get bit and sample-rate reduction, too), using serial or parallel routing.

There are eight filter types, including the usual low-pass and ladder filters, along with a keen Delay filter (read 'comb') and, new for the commercial version, a String filter and a crafty Phase Modulation Delay job. Everything we threw at the latter sounded as if it had been trampled by the BBC Radiophonic Workshop, which we mean as a compliment, of course.

Additional sound sculpting comes in the form of the obligatory effects bank. The beta version had delay, reverb and a limiter, but now you also get phaser, chorus, distortion and EQ. You also have full control over the processing chain via a nifty drag 'n' drop FX Order panel.

Modulation

Much of Helix's power lies in its multitude of modulation options. There are eight envelope generators, providing control over both the level and rate of the ADSR stages, and there's a second release stage thrown in for good measure.

Editing these was confusing in the beta version, but thankfully there's now a graphical display of the envelope contour.

Elsewhere, you'll find six LFOs: four are polyphonic and applied per voice, the remaining two global. There are 18 waveforms to choose from and you can adjust the phase and period/length (ie, rate) of each. The latter is defeated when the LFO is locked to the host tempo and replaced by a menu of note values. The four independent LFOs have attack, hold and release controls.

And, if that wasn't enough to twist your timbres beyond all hope, there's also a pair of bipolar sequencers, which can run free or in sync mode. The Lag (glide) is adjustable, and you can set it to run (and loop) for up to 16 steps.

More modulation is provided by MIDI CC and MIDI Learn functions. All 29 mod sources can be assigned in the Matrix, using the 42 modulation slots. Each slot allows for a single source, two destinations and a scale source. There are 57 destinations, though delay time isn't one of them, unfortunately.

Summary

As you may have gathered, Helix is very deep, approaching the complexity of modular instruments, and is likewise possessed of an in-depth, intricate and articulate sound.

A brief trundle through the 800+ presets (organised into banks and categories, such as lead, pad and so on) makes it clear that Helix is a world apart from the usual analogue emulation or average ROMpler. This is a synth of singular style and class, on a par with any we've heard.

Naturally, it's not perfect; not all of the waveshaping functions can be manipulated without causing audible artifacts - you only get the Morph function for crossfading the waves. Still, to get too hung up on this would be churlish in the face of the pure sound quality on offer.

Helix spent over a year as an open-source freeware beta plug-in, and while it isn't available via Audjoo's site anymore, it's still out there, if you want to use it.

For this reason, Helix may be its own worst competition. However, you can take it from us that the commercial version is worth far more than the asking price, and there's plenty here that you won't find in the free one. Highly recommended.

Check out these Helix audio examples:

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